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PSPICE - CNY17 optocoupler base connection??

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Junior Member level 2
Dec 17, 2012
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I have a CNY17 optocoupler model from Orcad's DK_DISCRETE.OLB library

when I try to simulate a circuit containing this optocoupler, I get a netlist error. I'm pretty sure it's because I don't have pin 6 (the base connection) connected to anything.

What do I connect it to? and why is it there?

Sometimes a simulator will not be happy until you add a token resistor at some spot.

A very high resistance to ground, or to another pin of the component, may do the trick.

I suspect you are doing the same thing as in your other thread - using parts intended for simply schematics or PCB layout which don't have Spice models associated with them.

I would suggest you find a tutorial on using Pspice and work through it first. Depending on the version of Orcad it may include a tutorial.


don't make me out to be clueless

my questions aren't "How do I perform a simulation in PSPICE". They are part-specific, library-specific, niche questions. I don't need a tutorial. They dont answer the questions I'm asking.

Connecting thru a big resistor to ground makes sense. But still, I want to know why there would be a base connection period.

I am not saying you are clueless (did I say that - I don't think so) but the problem you have sounds identical to your earlier one. Have you solved that problem? If not, you are probably facing the same issues. You don't yet seem to have found out how to view models associated with parts. You need to be able to associate models with schematic symbols for the simulations to work. The part you have used is out of the normal Orcad library for schematics/PCB layout I believe, so won't have a Spice model associated with it. I don't use Orcad/Pspice so cannot talk you through the process. I suggested a tutorial because that should explain the process of selecting the parts for simulation, associating models, creating new symbols and making sure the model pin order matches the symbols. If you know how to do that anyway then fine.

To answer you other question, the base connection is there so you can connect to it if your circuit demands it, but it shouldn't be a requirement. While simulators will give errors (such as "singular matrix") if you have floating nodes I wouldn't expect a floating transistor base to do that as leakages built into the device model will mean it isn't really floating. That does depend on how the model is constructed though.


I agree with Keith, it's not necessary to connect the CNY17 base terminal, unless you want to for a specific reason. There is a CNY17 simulation model in the pspice/opto.olb, by the way.

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